president obama and other world leaders have and alerted. bill: the whole dealo that took out the dinosaurs, they thought it was one of these astroid, right? what is the risk that they could say this this could happen again. >> it could happen again. a tron mores around the world are lookingout and into space all the time. knowledge is growing more and more as the years go by. those monitoring these near-earth objects, they say there are about a million astroids and meteors in earth's proximity and they are looking up all the time. >> we've seen and tracked about 9,000 of them right now, and about a thousand of them are potentially hazardous. we look at those carefully, and it turns out we are safe from those for many hundreds of years. >> reporter: a rock this size attributed to the 1908 event in russia that leveled trees and forests or hundreds of miles, bill. bill: let's hope it hits the ocean some time. phil, thank you. phil keating in miami on that. heather: i remember it starts out as an astroid, becomes a meter when it hits the atmosp